This invention relates to dust suppression generally and more particularly to coal dust suppression. The use of methacrylate polymers and hydrophobic liquids such as kerosene and diesel fuel, emulsified in water, for the purpose of dust suppression is disclosed. The instant emulsions control dusting and windage loss at stock piles and during material handling and transport, and are also effective when applied to hauling roads around coal preparation plants, mills, mining sites and the like.
Dust suppression, as used herein, is defined as the prevention or reduction of the extent to which fine particulates become airborne or suspended in air. Dust is generated in significant quantities during the mining, handling, transportation, and storage of coal; dust is also generated during the processing, transportation and handling of rock, ores (for example iron ore), grains, taconite, sulfur, copper, limestone, gypsum, flyash, cement, bauxite and fertilizers (such as potash and phosphates), among others. Road dust is also a problem.
In coal mining applications, mechanical and chemical methods for dust control are known. For example, dust collection equipment is used in mining operations. Also, water is commonly used to prevent dust particles from becoming airborne. Additionally, aqueous solutions containing surfactants may be used for dust control (see U.S. Pat. No. 3,690,727 and 4,136,050). Aqueous foam compositions have also been used to suppress dust (see U.S. Pat. Nos. 3,954,662, 4,000,992 and 4,400,220). U.S. Pat. No. 4,316,811 discloses the use of an aqueous solution of polyethylene oxide for dust control. U.S. Pat. No. 4,169,170 discloses the use of an aqueous composition comprising an asphalt emulsion or a black liquor lignin product and a water soluble methoxylated alkylphenol or sulfosuccinate wetting agent to form a crust layer which provides protection against the loss of coal due to wind or the action of a coal transportation device.
The instant invention relates to the use of at least one methacrylate polymer, at least one emulsifying surfactant and at least one hydrophobic liquid for dust suppression, especially coat dust suppression. This admixture is then emulsified into water, preferably at the application site, to provide a dust suppressant having excellent penetration, binding and wetting properties which also provides efficient and inexpensive coverage of the material being treated. After application, the dust control agent provides a tacky, water-resistant coating which effectively prevents dusting while additionally acting as an antifreeze agent. The instant discovery provides excellent dust suppression relative to contemporary dust suppressants.
The emulsions and method of the instant invention constitute a notable advance in the art since they minimize the disadvantages of commonly used dust suppressants, such as compositions comprising water and surfactants. These disadvantages include, but are not limited to: (1) low persistence--with light usage, dust control may be only temporary due to evaporation; (2) adverse affect on BTU values--with heavy application, the effective BTU value of the coal being treated may be reduced; (3) expense--known coat dust suppressants are costly; (4) freezing--many coal dust suppressants currently in use do not aid in the prevention of freezing, and may, in fact, contribute to freezing; and (5) spontaneous combustion--conventional coat dust suppressants may contribute to spontaneous combustion due to the heat of wetting.